Overrunning clutches are used in many applications in order to transfer torque between drive elements in one direction while allowing slipping and/or damping of torque perturbations in the other direction. The torque can be transferred by drive elements, such as endless traction elements, including belts or chains, or by a gear train via the overrunning clutch to a shaft of an element being driven. Such overrunning clutches are often used in connection with engine accessory drives, such as for an alternator, power steering pump, air conditioning compressor, or other driven element, for example in a motor vehicle.
Overunning clutches are also used in other applications in order to isolate or dampen reverse torques from being transferred to the driven assembly. Many overrunning clutches utilize rollers on ramp surfaces or rocker elements which engage with more force for rotation in one direction and loosen and allow reverse rotation in the other direction. These are used in connection with belt, chain, and/or gear drives. However, these overrunning clutches are complicated assemblies typically including hardened rollers or rockers that must be located between specifically formed surfaces and retained in position. Additionally, overrunning clutches do not provide any damping when they are operating in the overrunning mode.
It would be desirable to provide a simplified rotational damper which permits rotational damping between a drive element and a shaft to allow driving in a first direction and overrunning in a second direction with the additional capability to provide coulomb damping in the overrunning mode.